Systray Memory Display is a portable at-a-glance RAM indicator.

This utility sits down in the systray and provides you with an up-to-date percentage of how much memory your system is using. Through the settings (via right-click on the systray icon) you can configure Systray Memory Display's interval rate (ms) as well as text/background colors.

Systray Memory Display isn't reinventing the wheel, as you do have access to this information through your machine's task manager. The point here is to have it accessible at all times with minimal fuss - any settings you apply are saved to the root folder allowing you to use it on any machine by simply copying it a USB flash drive for instance.